Deviated wellbore drilling system and apparatus

Abstract

A deviated wellbore drilling system suitable for drilling curved wellbores which have a radius of curvature of approximately 200 to 1,000 feet relative to a vertical or near vertical wellbore comprises a drill string, a drill bit, and a fluid-operated drill motor having a curved or bent housing section for rotating the drill bit independently of the drill string. The drilling motor has an elongate tubular rotor/stator drive section containing a rubber stator and a steel rotor and the housing is bent or curved intermediate its ends. A straight or bent univeral section below the bent or curved rotor/stator section contains a universal joint for converting orbiting motion of the rotor to concentric rotary motion at the bit, and a bearing pack section below the universal section contains radial and thrust bearings to absorb the high loads applied to the bit.

We claim: 
     
       1. A system of apparatus for the drilling of a deviated wellbore into the earth comprising; a drill string extending into a well bore in the earth,   a fluid operated drill motor and drill bit operatively secured on the bottom end of said drill string,   said drill motor being connected at its upper end to said drill string and at its lower end to said drill bit for rotating said drill bit independently of rotation of said drill string,   said drill motor having a tubular drive section housing with the longitudinal axis of its upper end angularly displaced from the longitudinal axis of its lower end for directing the axis of rotation of said drill bit such that it is angularly displaced from the axis of said drill string for effecting a curved path for said wellbore,   said motor comprises a rubber stator in said housing and a steel rotor rotatable therein,   said stator having an upper end and a lower end, the longitudinal axis of its upper end angularly displaced from the longitudinal axis of its lower end such that said stator fits the angular configuration of said housing, and   said drill motor drive section housing directs the axis of said drill bit to effect a curved path having a radius of curvature of from approximately 200 to approximately 1,000 feet relative to a substantially vertical wellbore.   
     
     
       2. A system of apparatus according to claim 1 in which said motor drive section housing has a single bend intermediate its upper and lower ends.   
     
     
       3. A system of apparatus according to claim 1 in which said motor drive section housing has a plurality of vertically spaced bends between its upper and lower ends.   
     
     
       4. A system of apparatus according to claim 1 in which said motor drive section housing gradually curves between its upper and lower ends.   
     
     
       5. A system of apparatus according to claim 1 in which said drilling motor is a fluid-operated drilling motor including a rotor/stator section containing a rubber stator and a steel rotor,   said rotor/stator section having a tubular housing having a single bend intermediate its upper and lower ends so that the longitudinal axis of its upper end is angularly displaced from the longitudinal axis of its lower end for directing the axis of rotation of said drill bit such that it is angularly displaced from the axis of said drill string for effecting a curved path for said wellbore,   said stator being bent with said housing,   said rotor being straight, and   said rotor being sufficiently flexible and said stator being sufficiently compressible to permit rotation of said rotor without undue binding.   
     
     
       6. A system of apparatus according to claim 1 in which said drilling motor is a fluid-operated drilling motor including a rotor/stator section containing a rubber stator and a steel rotor,   said rotor/stator section having a tubular housing having a plurality of vertically spaced bends between its upper and lower ends so that the longitudinal axis of its upper end is angularly displaced form the longitudinal axis of its lower end for directing the axis of rotation of said drill bit such that it is angularly displaced from the axis of said drill string for effecting a curved path for said wellbore,   said stator being bent with said housing,   said rotor being straight, and   said rotor being sufficiently flexible and said stator being sufficiently compressible to permit rotation of said rotor without undue binding.   
     
     
       7. A system of apparatus according to claim 1 in which said drilling motor is a fluid-operated drilling motor including a rotor/stator section containing a rubber stator and a steel rotor,   said rotor/stator section having a tubular housing which gradually curves between its upper and lower ends so that the longitudinal axis of its upper end is angularly displaced from the longitudinal axis of its lower end for directing the axis of rotation of said drill bit such that it is angularly displaced from the axis of said drill string for effecting a curved path for said wellbore.   
     
     
       8. A system of apparatus according to claim 1 in which said drilling motor is a fluid-operated drilling motor including a rotor/stator section containing a rubber stator and a steel rotor,   said rotor/stator section having a tubular housing which gradually curves between its upper and lower ends so that the longitudinal axis of its upper end is angularly dispalced from the longitudinal axis of its lower end for directing the axis of rotation of said drill bit such that it is angularly displaced from the axis of said drill string for effecting a curved path for said wellbore,   said stator being curved with said housing,   said rotor being straight, and   said rotor being sufficiently flexible and said stator being sufficiently compressible to permit rotation of said rotor without undue binding.   
     
     
       9. A system of apparatus according to claim 1 in which said drilling motor is a fluid-operated drilling motor comprising a rotor/stator section containing a rubber stator and a steel rotor, a straight universal section therebelow which contains flexible connection means for converting orbiting motion of the rotor to concentric rotory motion at said drill bit, and a bearing pack section below the universal section containing radial and thrust bearings to absorb the high loads applied to said drill bit,   said rotor/stator section having a tubular housing with the longitudinal axis of the upper end angularly displaced from the longitudinal axis of the lower end for directing the axis of rotation of said drill bit such that it is angularly displaced from the axis of said drill string for effecting a curved path for said wellbore, and   said rotor being sufficiently flexible and said stator being sufficiently compressible to permit rotation of said rotor without undue binding.   
     
     
       10. A system of apparatus according to claim 9 in which the length of said rotor/stator section housing is from 2 to 3 times the length of said bearing pack section.   
     
     
       11. A fluid operated drill motor for the drilling of a deviated wellbore into the earth comprising; a motor housing having a rotor/stator drive section with the longitudinal axis of one end angularly displaced from the longitudinal axis of the other end,   a rubber stator in said housing rotor/stator drive section and a steel rotor rotatable therein,   said stator having an upper end and a lower end, the longitudinal axis of its upper end angularly displaced from the longitudinal axis of its lower end such that said stator fits the angular configuration of said housing rotor/stator drive section,   said motor being adapted to be supported on a drill string in a well bore and to support a drill bit on said rotor, whereby the axis of rotation of the drill bit is angularly displaced from the axis of the drill string for drilling the wellbore in a curved path on rotation of the rotor and bit and advancing the same into the wellbore, and   said drive section housing has an angular displacement sufficient to direct the axis of the drill bit in a curved path having a radius of curvature of from approximately 200 to approximately 1,000 feet relative to a substantially vertical wellbore.   
     
     
       12. A fluid operated drill motor for the drilling of a deviated wellbore into the earth according to claim 11 in which said motor drive section housing has a single bend intermediate its upper and lower ends.   
     
     
       13. A fluid operated drill motor for the drilling of a deviated wellbore into the earth according to claim 11 in which said rotor/stator housing drive section housing has a plurality of vertically spaced bends between its upper and lower ends.   
     
     
       14. A fluid operated drill motor for the drilling of a deviated wellbore into the earth according to claim 11 in which said motor drive section housing gradually curves between its upper and lower ends.   
     
     
       15. A fluid operated drill motor for the drilling of a deviated wellbore into the earth according to claim 11 in which said rotor/stator housing drive section is bent,   said stator being bent with said housing,   said rotor being straight, and   said rotor being sufficiently flexible and said stator being sufficiently compressible to permit rotation of said rotor without undue binding.   
     
     
       16. A fluid operated drill motor for the drilling of a deviated wellbore into the earth according to claim 11 in which said rotor/stator housing drive section is bent,   said stator being bent with said housing,   said rotor being straight,   said rotor being sufficiently flexible and said stator being sufficiently compressible to permit rotation of said rotor without undue binding,   said motor having a bearing pack section through which the rotor extends, and   the length of said rotor/stator section housing is from 2 to 3 times the length of said bearing pack section.